Bar lines are used to communicate structural information, here you will learn about the different types commonly used.
Bar lines are used to split a piece of music up into smaller sections and will always be found at the end of every bar. They are directly related to time signatures as the music shown between bar lines will always contain a set number of beats, which is determined by the given time signature. As well as showing these divisions of beats, bar lines can also be used to indicate that something is going to change within the piece, much in the same way road signs give you important information about what is coming up ahead. You will come across a few different types of bar line, all meaning something slightly different. These are shown below.
Standard Bar Lines
This is the most common and just shows the end of a bar. As mentioned above, there will be a set number of beats between each of these bar lines.
The remaining bar lines all function in the same way as a standard bar line in that they show the end of a bar but they all have a second purpose.
Double Bar Lines
As well as showing the end of a bar, the double bar line also tells you that you have reached the end of a structural section of a piece or song. An example of their use in a song could be at the end of a verse, chorus or any other main section.
Final Bar Lines
The final bar line does what it says on the tin. You will find it at the end of a piece or song. There will be nothing else to play after seeing one of these. This makes them quite useful for working out how many pages your song has if you get your sheets jumbled up! Just find the page that has the final bar line on it, and that will be the last one.
Dashed Bar Lines
The dashed bar line indicates the end of a phrase or sub-section within a longer song section, for example if a verse is split into two parts, this bar line will show the end of a section. If a section uses odd phrasing a dashed bar line will br used to indicate where the phrases ends.
Another common set of bar lines you will see are repeat marks. These are covered in this repeat marks lesson.
In some pieces of music, particularly when it comes to instructional sheets, there may be no bar lines shown. This indicates that rhythm isn't important in these sections and what is written will be played without a sense of pulse.